A common and well known form of threshing machine is the rotary combine. In a rotary combine, the grain or other crop harvested in the field is fed by a conveyor section into the threshing section containing the threshing rotor. The rotor itself is an elongated cylindrical member which may be positioned transversely or longitudinally of the direction of travel of the combine, but usually the latter. Thresher vanes or bars are permanently affixed to the outer surface of the rotor, usually arranged in a simple helical pattern, and it is those elements which do the work of separating the edible grain from the remaining plant material. Various agitators, shakers, graders, and screens are then utilized to further separate the different plant components.
In rotary threshing, it is customary to use different rotors for harvesting different crops. For example, a rotor having long straight and helical surface elements is most efficient for the harvesting of small grain, corn, and soybeans. On the other hand, a rotor having short helical sections is most efficient for the harvesting of rice, edible beans, and damp weedy crops. Use of a rotor mismatched to the particular crop being harvested can result in both inefficient waste of the primary crop, frequent jamming of the rotor and down time for the entire combine.
A typical combine is, of course, a rather massive and expensive vehicle. The rotor of a rotary combine is itself quite heavy and unwieldy, weighing far in excess of what might be liftable manually by a number of people. Even assuming then that a number of different rotors are at hand, the changing of one rotor for another in a given combine is a difficult operation requiring the use of auxiliary lifting cranes, or the like. Frequently, the practical effect of this situation is to severely limit the harvesting applications for which a combine can be used.
It would be most desirable if a single rotary combine could be readily adapted or converted for a wide variety of harvesting applications as required. Similarly, it would be most desirable if the ready convertibility of the combine could be accomplished without removal of the threshing rotor therefrom.